Clinical value of signal averaged electrocardiogram for the prediction of ventricular tachycardia after myocardial infarction

: One of the most important predictors for mortality after myocardial infarction is the occurrence of malignant ventricular tachyarrhythmias. Reentry has been shown to play a major role in the development of ventricular tachycardia (VT) in the chronic phase of myocardial infarction. Signal averaged electrocardiogram (SAE) may reveal the substrate for VT, that is, the delayed and fragmented ventricular activation around the infarcted area. Since Simson's report, the relation between the detection of late potentials (LP) on the SAE and the occurrence of VT in the chronic phase of myocardial infarction has been described by many authors. In these reports, the result that the absence of LP can predict the lower risk for VT has been emphasized. However, several factors such as time of SAE recording, infarct location, effect of reperfusion therapy, infarct size, and ventricular function may modify the SAE findings. Accordingly, further prospective study considering these factors is needed to establish the clinical value of SAE after myocardial infarction.